1. Department of Epidemiology, Fielding School of Public Health, University of California, Los Angeles, CA, USA
2. Division of Epidemiology and Biostatistics, School of Public Health and Family Medicine, University of Cape Town, Observatory, South Africa
3. Division of Infectious Diseases, Geffen School of Medicine, University of California, Los Angeles, CA, USA
4. Department of Family Medicine, Geffen School of Medicine, University of California, Los Angeles, CA, USA
5. Department of Psychiatry, University of Cape Town, Cape Town, South Africa
6. Mailman School of Public Health, ICAP at Columbia University, Columbia University, New York, NY, USA
7. Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA